GCSEChemistry: Combined ScienceOCR GatewayTopic Questions6.Global Challenges6.2 Organic Chemistry

Organic Chemistry (OCR Gateway GCSE Chemistry: Combined Science)

Topic Questions

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12 marks

A student did an experiment to prove that methane gas, CH4, produces carbon dioxide and water when it burns.

Look at the diagram of her experiment.

q21-paper-4-june-2019-ocr-gcse-chem

a)
The limewater turned milky showing that carbon dioxide had been formed.

A small amount of a colourless liquid condensed in boiling tube X. The student said that this proved that burning methane produced water.

The teacher said that the experiment had been set up incorrectly.

The teacher said that the student’s conclusion about water was not valid.

Describe and explain how the student could change how the experiment is set up to prove that water is produced by burning methane.

[2]

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1a2 marks
a)
A student has two test tubes. One contains ethane and one contains ethene.

q17c-paper-2-june-2019-ocr-gcse-chem

The student added bromine water to each test tube.

Describe what she observes.

Ethane ........................................

Ethene ........................................

[2]

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1b1 mark
b)
Ethane belongs to the homologous series called the alkanes.

What is the name of the homologous series that ethene belongs to?

[1]

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2a4 marks

Crude oil is used as a source of fuels. It is separated into many fractions by fractional distillation.

The diagram shows a fractionating column.

q18-paper-2-specimen-2016-ocr-gcse-chem

a)
Crude oil contains a mixture of hydrocarbons that boil at different temperatures.

Describe how crude oil can be separated using a fractionating column.
[4]

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2b1 mark
b)
Alkenes are used to make polymers. Polymers are used to make clothes such as socks and jumpers.

Suggest one property of a polymer that makes it suitable for making clothes.
[1]

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3a2 marks

Fractional distillation separates crude oil into useful fractions.

Look at the table.

It shows the percentage of each fraction made from crude oil. It also shows the percentage of each fraction needed for everyday uses.

Fraction Percentage made by
fractional distillation		 Percentage needed for
everyday uses
Gases 4 11
Petrol 11 22
Naphtha 10 18
Paraffin 12 20
Fuel oil 22 10
Waxes and tar 23 4

a)

i)

Which fraction is made in the greatest percentage?

Tick (✓) one box

Gases square
Petrol square
Naphtha square
Paraffin square
Fuel oil square
Waxes and tar square

ii)
Which fraction is needed in the smallest percentage?

Tick (✓) one box.

Gases square
Petrol square
Naphtha square
Paraffin square
Fuel oil square
Waxes and tar square

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3b3 marks
b)
Cracking changes large hydrocarbon molecules into smaller hydrocarbon molecules.

i)
One of the conditions needed for cracking is a high pressure.

Write down one other condition needed.

[1]

ii)
Cracking is a very useful reaction.

Explain why.

Use information from the table in your answer

[2]

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3c
Sme Calculator3 marks
c)
In 2008 the USA produced 4 900 000 barrels of crude oil per day. In 2019 this had increased to 11 000 000 barrels of crude oil per day.

Calculate the percentage increase in the number of barrels of crude oil produced per day from 2008 to 2019.

Use the formula: percentage increase =  increase over original× 100

Give your answer to 2 decimal places.

Percentage increase = ..................................................... % [3]

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4a1 mark

Crude oil is separated into useful fractions using fractional distillation.

The table shows the percentages of crude oil fractions from different oil wells.

Fraction Percentage of fraction in crude oil
Oil well X Oil well Y Oil well Z
LPG 2 7 10
Petrol 3 10 25
Paraffin 6 15 20
Diesel 7 11 15
Fuel oil 26 29 28
Bitumen 56 28 2

a)
Which oil well contains the highest percentage of low boiling point fractions?

Tick (✓) one box.

X     square

Y     square

Z     square

[1]

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4b
Sme Calculator2 marks
b)
A barrel of crude oil from oil well Y has a mass of 139 kg.

Calculate the mass of fuel oil in this barrel.

Mass = ..................................................... kg

[2]

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4c3 marks
c)
A sample of decane was cracked.

Look at the diagram of the apparatus used.

q20d-paper-2-june-2019-ocr-gcse-chem

i)
Describe how this apparatus is used to produce ethene from decane.
[2]
ii)
One molecule of decane, C10H22, produced two molecules of ethene, C2H4, and one molecule of product Z.

C10H22rightwards arrow 2C2H4 + product Z

Write the formula for product Z.
[1]

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56 marks
a)

Propane gas is used as a fuel for cooking and heating in caravans.

q22c-paper-2-nov-2020-ocr-gcse-chem

Incomplete combustion of propane can occur if the campers do not take sensible precautions.

Describe how incomplete combustion of hydrocarbons such as propane happens and the problems it can cause for campers.

Include a balanced symbol equation in your answer.

[6]

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6a3 marks

This question is about life-cycle assessment.

a)
A car company is developing three new cars:

  • A petrol car
  • A diesel car
  • An electric car.

They do a life-cycle assessment of each car.

Look at the information about the life-cycle assessment of each car.

q24a-paper-2-june-2018-ocr-gcse-chem

The company decides to manufacture and sell the electric car.

Explain why they make this choice.

Use the information from the life-cycle assessment to help you.

[3]

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6b3 marks
b)
The fuels for the petrol and diesel cars are made from crude oil.

Crude oil is separated into different parts by fractional distillation.

The diagram shows a fractionating column.

q24b-paper-2-june-2018-ocr-gcse-chem

Explain why crude oil vapour can be separated by fractional distillation.

[3]

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6c2 marks
c)
The table shows the boiling points of molecules present in different crude oil fractions.

Molecule Boiling point (°C)
A −2
B 125
C 216
D 502

Which molecule, A, B, C or D, is in the LPG fraction?

Explain your decision.

[2]

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71 mark

A student is using the internet to find out about alcohols. The student finds the following information.

Name Number of carbon atoms Boiling point
(°C)
Methanol 1 65
Ethanol 2 79
Propanol 3 97
Pentanol 5 138
Hexanol 6 156

a)
Plot a graph of the boiling points of the alcohols on the grid. Draw a line of best fit.

q25a-paper-2-june-2018-ocr-gcse-chem

[3]

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8a2 marks

Poly(propenenitrile) is an addition polymer.

Look at the flow chart. It shows how poly(propenenitrile) is made from crude oil.

q20-paper-4-specimen-2016-ocr-gcse-chem

a)
Crude oil is a mixture of hydrocarbons.

Fractional distillation separates the hydrocarbons in this mixture.

Explain how fractional distillation separates the hydrocarbons, in terms of intermolecular forces.

[2]

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8b1 mark
b)

Look at the displayed formula for propenenitrile.

q20b-paper-4-specimen-2016-ocr-gcse-chem

How can you tell from the displayed formula that propenenitrile is an unsaturated compound?

[1]

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91 mark
a)
Butene is an alkene.

What is the general formula for an alkene?
[1]

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106 marks
a)
A student has unlabelled samples of three liquids.

The student knows that the three liquids are:
  • pentane, C5H12
  • pentene, C5H10
  • ethanoic acid, CH3COOH.

Describe tests that the student should do to identify each of the three liquids.

Include balanced symbol equations for the reactions described.

[6]

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